Rod Elliott's Project 27 and Amp

[Roly]

Re: groundin2.jpg - well we are half way there.  The green earth/ground/common is radial as it should be, but you show the red and orange +/-25V daisy-chained.  These should also distribute radially like the green ground side.  Buss connection of +ve and -ve is not permissible (for exactly the same avoiding "resistance-in-common" reason).

The "other earths" are your green wires (the mains earth being your blue wire).

Um ... are you really running your effects boards at +/-25 volts?

Looking again at your a222.jpg it looks like you are using on-board regulators for each board (can't see all of the Phaser board but I assume it also has a 3-pin regulator out of frame).  If this is the case then you can simply daisy-chain the supply because each board will be isolated from unwanted supply signals by their respective regulators.

I have spotted one other thing; on your p27 board one of the zeners is cuddling up to an electrolytic cap, and this isn't a healthy relationship for either of them.  Zeners get hot and like free air around them to keep cool, and electro caps don't like getting hot.  In general I try to give components that are going to get a bit hot, zeners, their series resistors, 3-pin regulators, etc., a bit of "breathing space", and also mount them so that they are a few millimetres up off the board rather than hard down on it (because over time they will also bake the board).

There is another little trap with 3-pin regulators; they require a couple of small caps, 0.01uF-0.1uF, connected between their input pin and ground, and their output pin and ground, as close as possible to the IC, otherwise you might get mysterious oscillations on your "regulated" supply rails.  On your boards this may now be easiest on the copper side.

[ghoshsubha444@gmail.com]

Thanks Roly..

well we are half way there.  The green earth/ground/common is radial as it should be, but you show the red and orange +/-25V daisy-chained.  These should also distribute radially like the green ground side.  Buss connection of +ve and -ve is not permissible (for exactly the same avoiding "resistance-in-common" reason).

Understood.

The "other earths" are your green wires (the mains earth being your blue wire).

ok.

Looking again at your a222.jpg it looks like you are using on-board regulators for each board (can't see all of the Phaser board but I assume it also has a 3-pin regulator out of frame).  If this is the case then you can simply daisy-chain the supply because each board will be isolated from unwanted supply signals by their respective regulators.

yea for complexity i ignored drawing 9v line. i run effects boards @9v

I have spotted one other thing; on your p27 board one of the zeners is cuddling up to an electrolytic cap, and this isn't a healthy relationship for either of them.  Zeners get hot and like free air around them to keep cool, and electro caps don't like getting hot.  In general I try to give components that are going to get a bit hot, zeners, their series resistors, 3-pin regulators, etc., a bit of "breathing space", and also mount them so that they are a few millimetres up off the board rather than hard down on it (because over time they will also bake the board).

Eagle eyed!! 8|
I am modifying my pcb drawing and will obviously allow more spaces between hot items.


I am again drawing my power supply pcb to rectify earlier error. Will post here as i am done.

1.I am encountering a problem something known as bouncing. whenever i am changing/twisting my ceiling fan regulator I am getting heavy popping sound. Start up popping is not possible since i have used relay delay in my power amp?

2.whenever i am disconnecting the mains earth from the ground the noise is increasing hugely. Is this usual or is this because of noise in power line? if this is usual then how amps like Roland cube 15 with 2 pin in the plug exist?(apart from they are well isolated).

My current psu picture is attached..

[Roly]

Eagle eyed!! 8|

I have been playing this game for rather a long time now.   

1 & 2 - it seems that your amp is still spread all over your bench, and until it is mounted in an earthed metal chassis it is wide open to anything that comes along.

When an appliance is turned on or off there is a small spark in the switch, and apart from conducting a mess of radio frequencies along the house wiring this also directly radiates signals. 

Once the amp is on a grounded/earthed metal chassis it will be much better shielded against direct radiation, but even when the lid is screwed down it is quite possible for "mains-borne" interference to enter the amp via the mains wiring and still cause pops and splats - fridge thermostats are a well known source of such pops, but electric drills, food processors, vacuume cleaners etc., all can produce pops and whines, and may not even be in your house.  This is why is is fairly common practice these days to use some form of mains filter where the power enters the amp.

A simple and safe way to bring the mains in is via an IEC connector, and these are available in various sorts including fused, and with mains filters.  A free source of these is to scrounge dead computer power supplies.  Not all have filtered IEC sockets, but if you collect a few you should be able to find one.  Computer repairers here are only too happy for you to take dead power supplies off their hands, and even blown up ones still contain a lot of perfectly working components for the tinkerer.  I use the main capacitors in valve amplifier builds, the cases make good project boxes, and of course all those coloured wires mean you will never have to buy hookup wire ever again.



Since you are going to take care of putting hot things close to caps I'll just comment that heatsinks need surface area to be effective - just bolting a lump of ali to a regulator won't actually couple a lot of heat to the air; a heatsink is a coupler that couples the device to the surrounding air, not a magic heat vanisher.  Again, computer power supplies normally contain several.

[ghoshsubha444@gmail.com]

Ok Sir. I will give a look into my old SMPS.

I have tried to draw a new PCB for power supply but it is quite a headache 

So, I have tried to draw an image to depict the order of components in my earlier homemade PCB.

Please check my attachment.. and suggest if my earlier arrangement was wrong..If something seiously wrong then have to redraw it

[phatt]

My Advice FWIW;
Loose those extra resistors across line and for Gods sakes Put the damn thing in a metal case of some sorts otherwise you WILL go in circles for a very long time.

All this PSU stuff is Clearly explained on ESP site if you care to note!

Phil.

[J M Fahey]

Well, those extra .1uF and 2K2 resistors won't hurt 
BUT yes, put it in some kind of chassis or you'll never even start to fight noise.

A chassis can be as simple as a sheet of 1mm or 1.5mm aluminum, with one edge bent and perforated to act as a front panel and hold jacks, pots , switches, etc.

As of a simple PSU, no actual PCB is needed, for ages I just contact cement glued filter caps to the chassis, and soldered 4 rectifier tubes ti proper cap legs, go figure.
"Silastic" type transparent silicone sealant also works very well.
In fact, works better, only it takes at least overnight to dry.
And .1 bypass and 2K2 discharge resistors (if you want to use them) can be soldered straight pin-to-pin .

Or get a dead amplifier, DVD player, PC case cover, etc. and turn it into a makeshift chassis.

A dead guitar amp would be perfect.

[Roly]

The reason @phatt deleted those components is because;

a) the supplies will always be connected to their load so bleeder resistors are not required.  These are only required in bench power supplies which may not have a load connected, and in valve/tube amps where the heaters cool on power down and may leave dangerous voltages on the supply capacitors.

b) the 0.1uF are high frequency bypasses.  The connection wires to the load have inductance so these should properly go right at the device that needs them to keep the high frequency (and radio frequency) bypass paths as short as possible.  They won't do any harm in the power supply, they just may not do any good.  These should go right at the IC, often mounted on the copper side, between +ve and -ve for op-amps, and between +ve supply and ground for logic IC's.  Anything from about 0.01uF up will suffice.

Without a metal chassis trying to fight noise pickup is like trying to bail out the ocean.  VCR's are now a throwout item here and many of the earlier ones had a large metal chassis which make an excellent testbed, or move forward into your final metal chassis ... now.

"Silastic" is wonderful stuff, but anywhere you want to use it in direct contact with copper (such as sticking down PCB's) make sure you use "neutral cure", the acetic acid stuff is fine for general gluing but will attack copper.

[phatt]

The reason @phatt deleted those components is because;

He Did?
Well I'll be darned, I got something right.  :cheesy:

I kinda knew the bit about the bleed resistor but was not sure how to word it.
So I'm glad you cleared the air on that.
I think for me I learn a lot from example from chaps like you.

I now see the point about the hifreq caps being at the device.
So I learn *Why* which is all good.

For goshshuba,,
I think *Teemu's book* explains the ground path layout stuff fairly well,,Might make for some good reading while you are scrounging for a metal case.

http://www.ssguitar.com/index.php?topic=711.0

Judging by the amount of stuff you have already built I'd say the case will get plenty of use because if you are like me the last thing you build is just the prototype for the next brain wave idea and having all the case/knobs/sockets/psu stuff already setup up really speeds up the process of prototyping.

my proto cases are reused many times over and they end up full of holes for knobs.
Yes plus 1 on Old VCR stuff. they also often have a lot of shielded cable just perfect lengths for small audio wire ups.

Some years back I built a 6V6 Amp from old transformers that where given to me and that chassis had so many modifications during the build that I had more holes than metal on the front.
I had to make a new case before I finally mounted it all in an Amp head. :cheesy:

Keep at it chum, it will all become clear to you in the end. It took me a long time to get my head around circuit layout which is not as simple as it first looks.
Have fun, Phil.

[ghoshsubha444@gmail.com]

my proto cases are reused many times over and they end up full of holes for knobs.
Yes plus 1 on Old VCR stuff. they also often have a lot of shielded cable just perfect lengths for small audio wire ups.

Some years back I built a 6V6 Amp from old transformers that where given to me and that chassis had so many modifications during the build that I had more holes than metal on the front.
I had to make a new case before I finally mounted it all in an Amp head. :cheesy:

Keep at it chum, it will all become clear to you in the end. It took me a long time to get my head around circuit layout which is not as simple as it first looks.
Have fun, Phil.

I am 200% agree with you. Till date i have spent almost double money on this than I presume. With this money I could have purchased a decent amp for sure! But who cares.  Its my money and DIY spirit that I care.

BTW, according to your suggestion I have somehow managed to find a spare SMPS case[photo attached]. Where I put PSU circuit. Do I have to put entire circuit on the case. If so, then I have to look for some bigger case like OLD VCR. But as the noise is concern, no improvement yet. Even I have tried to connect a 0.1 cap between +ve and -ve pin of the opamp.

Today i did a connection from computer to Amp with master volume almost set to 0. Its awful. But as I already know that guitar amp dosen't sound like hi-fi speaker.

Made a connection with keyboard too. Sound not bad. But not so good like the inbuilt speaker of the keyboard.

[phatt]

OK good cheap metal case,,, But Why is that ground lug that (I assume) comes from Earth pin from the IEC socket floating in space? (The Green Yellow wire with eyelet) 8|

Yes I do see where the earth for psu and common for circuit all join up but You MUST have it all tied back to the ground plug as well otherwise you have a floating Zero volts that is not grounded to EARTH pin and it will likely hum like mad.
Phil.

Edit,, whoopsy. yes I now see that the Mains socket is not in use,, but still the mains EARTH must connect to the case otherwise hum.

[ghoshsubha444@gmail.com]

OK good cheap metal case,,, But Why is that ground lug that (I assume) comes from Earth pin from the IEC socket floating in space? (The Green Yellow wire with eyelet) 8|

Yes I do see where the earth for psu and common for circuit all join up but You MUST have it all tied back to the ground plug as well otherwise you have a floating Zero volts that is not grounded to EARTH pin and it will likely hum like mad.
Phil.

Edit,, whoopsy. yes I now see that the Mains socket is not in use,, but still the mains EARTH must connect to the case otherwise hum.

Thanks for examining...

The Blue color wire is the main earth which is first attached to the chassis with a screw and from there a short black wire goes to Com ground where several wires are tied together. Similarly all +25v -25v +9v are all tied together and connected to their respective position as a single point.. Please refer to  my earlier attachment.

[Roly]

If you're paying attention you can go a long way in electronics on intuition - I know I did.

I had more holes than metal on the front.

I think I can just fit another hole ... there ...
{drilldrilldrill - clang}
Oh dear, the front panel just fell in half.

Till date i have spent almost double money on this than I presume.

Murphy's Law of projects - anything worthwhile costs twice as much and takes twice as long -  except software where you double that.

but still the mains EARTH must connect to the case otherwise hum.

...and possibly otherwise dead.

ghoshsubha, repeat after me, "the strings on my guitar are connected to amplifier common, therefore it is vital that amplifier common is securely connected to mains safety earth, lest I become an unwilling part of the light show".

I know nothing about Indian power mains practice; please post pic of plug and outlet - what voltage and frequency?


{this gives me the leaping jeebies :crazy2:}

The Blue color wire is the main earth

I've just looked up the standard colours used in India and blue is for a phase active (as it is here).

Mains safety earth is green (or now green with a yellow stripe here) so it is unmistakable.

Mains safety earth must be equal or heavier conductor to the mains active, and it is good practice to use the proper colours for mains wiring within equipment.  Heavy duty green should be used for mains safety earth and for nothing else (and no other colour should be used for mains safety earth).  For the amplifier common runs black is fine.

[ghoshsubha444@gmail.com]

hello..

I dont know about if I am doing any mistake on other things but I can 500% assure you that mains earth is first attached to the chassis and from there to the common ground.


I have really messed a lot with wires and colors but when I will be done with the experimentation I will definitely set up the whole thing with proper color wires with neat arrangement.

Mains Voltage:220V @ 50Hz
Thanks for the care <3) <3)

[ghoshsubha444@gmail.com]

compressor

[Roly]

Thanks for the care <3) <3)

Getting killed can seriously cut into your guitar noodling time.   

Why am I not surprised to see an older style English mains plug?

{when I lived there I had to change all the plugs every time we moved house because there were at least three different "standards" in use, small round pin, large round pin (like yours), and rectangular pin which now seems to be the dominant standard.  I've seen some English wiring and switchboards that date back to the Roman invasion and make the guy up the ladder look cutting edge.  }

Grab an old computer case, glue/bolt/BluTac boards inside.  Profit!   :dbtu: